基于ZL116支座补焊开裂失效分析与改进

Failure analysis and improvement of repair welding of cracks based on ZL116 bearing

某型号飞机使用过程中检查发现,排气门电机固定支座有疑似裂纹,经清洗后着色检查,有穿透性裂纹。支座材料牌号为АЛ34(国产化牌号为ZL116),热处理要求为σb≥294 MPa,表面处理要求为硫酸阳极化,重铬酸盐填充/涂底漆。支座处于发动机舱上方,受较大的振动影响。通过故障支座外观观察、体视检查、微观观察、能谱分析、金相检查、硬度测试等试验得出结论,支座疲劳开裂,疲劳产生的主要原因是应力集中,由于焊接缺陷的存在导致裂纹快速扩展,是支座疲劳裂纹形成的直接原因。根据分析结果,给出提高支座受力部位的疲劳抗力,避免故障再次发生的有效方法,并提出了预防建议。

A certain type of aircraft is inspected during use,it is found that exhaust valve motor fixed bearing has suspected crack.After the cleaning,the dye penetrant inspection finds penetrative cracks.The bearing material grade isАЛ34(domestically produced grade is ZL116),the heat treatment requirement isσb≥294 MPa,and the surface treatment requirements are anodizing sulfuric acid and dichromate filling/priming.The bearing is above the engine compartment and is subject to relatively large vibrations.Through the observation of the fault bearing appearance,stereo inspection,microscopic observation,energy spectrum analysis,metallographic exami-nation,hardness test and other tests,it is concluded that the bearing has fatigue crack,and the main cause of fatigue is stress conc-entration.Due to the existence of welding defects,the cracks expand rapidly,which is the direct cause of the formation of fatigue cracks.According to the analysis results,a effective method is given to improve the fatigue resistance of the bearing parts and avoid the recurrence of faults.And prevention advice is also put forward.